台湾海峡游泳动物种类组成及其多样性

根据2006-2007年在台湾海峡进行的四个季度航次定点底拖网调查资料,分析了台湾海峡游泳动物的种类组成、数量分布、优势种和多样性等特征。结果表明,调查海域共鉴定出游泳动物373种,其中鱼类273种,甲壳类81种,头足类19种;渔获物组成以鱼类为主,占渔获物总重量的65.6%,其次为甲壳类和头足类,分别占21.1%和13.3%,所有调查站位游泳动物的年平均生物量密度指数为24.91kg/h,主要优势种类为带鱼(Trichiurus japoni-cus)、拥剑梭子蟹(Portunus haanii)、二长棘鲷(Parargyrops edita)、龙头鱼(Harpadon nehereus)、竹筴鱼(Trachurus japonicus)、火枪乌贼(Loligo beka)等。对多样性的分析显示,台湾海峡游泳动物物种多样性指数(H′)变化范围为1.45-3.21,平均为2.47,其中秋季最高,夏季最低,且呈现南高北低的特点。与历史资料相比,目前台湾海峡游泳动物种类数明显减少,尤其是闽东和闽南—台湾浅滩海域表现最为突出;优势种类个体呈现小型化和低龄化趋势,表明台湾海峡游泳动物资源衰退明显。

Nekton species composition and biodiversity in Taiwan Strait

Based on four bottom trawl surveys(2006-2007) in the Taiwan Strait,nekton species composition,biomass and density distribution,dominant species,and community characteristics were analyzed.We re-corded 373 nektonic species including 273 fish species,81 crustaceans and 19 cephalopods.The mean bio-mass density index of the study area was estimated to be 24.91 kg/h with fish species,crustacean species and cephalopod species accounting for 65.6%,21.1% and 13.3% of the total,respectively.Dominant species in-cluded Trichiurus japonicus,Portunus haanii,Parargyrops edita,Harpadon nehereus,Trachurus japonicus and Loligo beka.Shannon-Wiener diversity indices(H’) ranged from 1.45 to 3.21,with an average of 2.47 and were higher in autumn and winter than in spring and summer.Compared with historical data,nekton resources are obviously declining,with species richness decreasing especially in the Minnan-Taiwan Bank area.Domi-nant species also exhibited a preponderance of smaller size and age classes compared to historical data.